Duckwall, Jr., in U.S. Pat. No. 4,405,819, has proposed obtaining alcohols from acids, which can be branched, using a metal-containing hydrogenation catalyst. However, the process requires a sweep gas, containing carbon monoxide.
Wall has recited, in U.S. Pat. No. 4,149,021, the hydrogenation of esters, apparently of linear acids, using a cobalt/zinc/copper catalyst. The use of a copper/zinc oxide catalyst is said to be undesirable, because of catalyst instability.
Wilkes has disclosed, in U.S. Pat. No. 4,283,581, a process for hydrogenating feed stocks, such as glycolide and glycolates, to ethylene glycol, using a copper/zinc oxide catalyst, supported on silica. The reference indicates that, using a similar copper/zinc oxide/alumina catalyst, low conversions are obtained at about 190.degree. C. and a pressure of 105 Kg/cm.sup.2. Higher conversion (46%) was reported at a higher temperature.
The reduction of branched esters, e.g., pivalic acid esters, to alcohols, has been disclosed by Kurhajec in U.S. Pat. No. 2,986,577. A copper chromite catalyst was employed. The reaction required a high hydrogen pressure, of the order of 232 Kg/cm.sup.2.
Pine et al. (U.S. Pat. No. 3,361,832) have accomplished conversion of branched acids, generally in the form of esters, to alcohols employing a molybdenum sulfide catalyst, under relatively low temperatures and pressures. However, for high selectivity toward corresponding alcohols, e.g., neoheptanol, the use of high pressures, well above about 70 Kg/cm.sup.2, are required.
Landa et al., Chem. Listy, vol. 51 (1957), 452-458, have recited obtaining small amounts of neopentanol by hydrogenation of methyl pivalate, using Adkins' copper-chromium oxide catalyst, J. Am. Chem. Soc., vol 72 (1950), 2626-2629.
Reduction of alpha,alpha-dimethylalkanoic acids over copper chromite catalyst has been recited by Puzitskii et al., Neftekhimiya, vol. 7(2) (1967), 280-285. Reduction of methyl pivalate to neopentyl alcohol over copper chromite has been reported by Shutikova et al., Tr. Vses. Nauch.-Issled. Inst. Natur. Dushist. Veshchestv, no. 7 (1965), 16-20.
Catalytic reduction of acids, having branched structures, other than of the alpha,alpha,alpha-trisubstituted type, are disclosed by:
______________________________________ U.S. Pat. No. 2,607,807 Ford et al. U.S. Pat. No. 3,478,112 Adam et al. U.S. Pat. No. 3,920,766 Jubin, Jr. et al. U.S. Pat. No. 4,433,175 Kaufhold ______________________________________
Hydrogenation of linear acids or their esters to corresponding alcohols as been disclosed in:
______________________________________ U.S. Pat. No. 1,839,974 Lazier U.S. Pat. No. 2,091,800 Adkins et al. U.S. Pat. No. 2,110,483 Guyer et al. U.S. Pat. No. 2,275,152 Lazier U.S. Pat. No. 2,340,688 Richardson et al. U.S. Pat. No. 3,985,814 Dougherty U.S. Pat. No. 4,104,478 Trivedi U.S. Pat. No. 4,398,039 Pesa et al. U.S. Pat. No. 4,443,639 Pesa et al. Japan Patent 57032237-A Sumitomo Chemical K.K. German OLS 2,613,226 Demmering (September 9, 1977) WO 82/03854 Davy McKee Soviet Union Patent 899113 Sultanov et al. Vedage et al., J. Catalysis, vol. 77 (1982), page 558. ______________________________________
Of the foregoing, the Vedage et al. article discloses employing a copper/zinc oxide catalyst, normally used for methanol synthesis, to hydrogenate propanoic acid to propanol. The Davy McKee patent is of similar interest with respect to reduction of butyl butyrate or other esters. The reference contemplates reduction of branched esters, e.g., isobutyrates.
It is accordingly apparent that there is a need for improved syntheses of highly branched alkanols, particularly of the neoalkanol type, from readily available substrates such as neoacids, rather than from esters or other precursors.